AIM. To combine what is being learned of ion transport through individual ionic channels across cellular membranes with recent advances in the elucidation of transmembrane structures. To produce a definitive volume on this subject first as a Study Book of galleys of posters and papers presented, then [within 3 months] as a final (hardback) proceedings book of corrected texts and edited transcribed discussion. METHOD: The Biophysical Discussions use a unique format whereby (a) the complete texts of all contributions are circulated in advance to all participants; (b) the actual meeting time is devoted entirely to discussion (not format talks); (c) a transcription of plenary debate is made and incorporated into the final proceedings volume. Authors of the 18 plenary papers and 65 posters are selected competitively from abstracts submitted in response to a general international call. Participants are limited to 200. Texts of the papers and 2-page poster summary texts plus edited transcripts of the debate comprise a final procedings book, fully indexed, also published as the January, 1984 issue of the Biophysical Journal, ensuring ease of reference and wide readership. This conference is fourth in a series of highly successful discussions. LONG TERM OBJECTIVES: Because membrane transport phenomena affect virtually all cellular processes, they are the object of attack from several, sometimes isolated, research directions. We hope in this meeting to bring together work from two of the most active areas of progress: the electrical characterization of ionic movement, and the structural determination of ion transport sites. The long-term problem to be resolved is the relation of membrane structure to the controlled ionic movement. The Organizers hope to effect communication between practitioners of various techniques. Circulated advance galleys of discussion texts will enhance such interdisciplinary Circulated advance galleys of discussion texts will enhance such interdisciplinary exchange, as each side has a chance to study the vocabulary as well as the data of the others before the actual conference. This leads to useful (transcribed) debate.